A low voltage bandgap reference circuit is illustrated and described in U.S. Pat. No. 7,113,025, which is herein incorporated by reference in its entirety. More specifically, this voltage reference circuit includes a proportional to absolute temperature (PTAT) voltage generating means that generates a PTAT voltage and a complementary to absolute temperature (CTAT) voltage generating means generates a CTAT voltage. Additionally, this voltage reference circuit includes a temperature coefficient determining means that interconnects the PTAT voltage generating means and the CTAT voltage generating means. With this voltage reference circuit, a reference voltage approaching that of a forward-biased diode can be generated without the disadvantages of a fractional VBE approach.
However, this reference voltage circuit assumes a negligible device input current. This assumption of a negligible input current was consistent with the properties of the MOSFETs with thicker gate oxides at the time of U.S. Pat. No. 7,113,025, but no longer holds for all cases. For example, non-negligible input current can flow into or out of the gate terminal of metal oxide semiconductor field effect transistors (MOSFETs) with very thin gate oxides and also into or out of the base terminal of bipolar junction transistors (BJTs). This non-negligible input current can cause imbalance and unpredictability to the circuits that make up the voltage reference. This could negatively affect the characteristics of the output voltage. This non-negligible input current also may have a temperature coefficient that could affect the output voltage of the voltage reference circuit.